1. Field of the Invention
The invention relates to a process for preparing carboxylic acid derivatives from carbonitriles and alcohols at elevated temperatures on titanium oxide catalysts.
2. Description of the Related Art
DE-A 27 14 767 discloses a process for preparing carboxylic acid derivatives by gas-phase reaction of nitrites with alcohols and water on solid, metal-containing catalysts such as copper, zinc, chromium, bismuth, manganese, iron, nickel, cadmium on carriers such as Al.sub.2 O.sub.3, SiO.sub.2, ZrO.sub.2 or TiO.sub.2. Dehydration and etherification are found as side reactions.
EP-A 412 310, for example, discloses a process for preparing carboxamides by hydration of nitrites with water on manganese-containing catalysts, which can subsequently be reacted with alcohols by acid catalysis, in the presence of metal salts, eg. as disclosed in U.S. Pat. No. 4,613,684, or in the gas phase on solid catalysts, eg. as disclosed in EP-A 561 614, or with formic ester resulting in formamide formation, eg. as disclosed in EP-A 392 361, on metal oxides to give the carboxylic acid derivatives.
The disadvantages for industrial application are the two stages and the formation of byproducts, such as production of salt or formamide formation.
DE-A 43 39 648 discloses a process for preparing caprolactam (a cyclic amide) by reacting aminocapronitrile with water in an ethanolic solution on a titanium oxide catalyst.